This mineral keeps red blood cells working and healthy. Breast milk and formula are usually adequate sources up to 6 months. Teen girls need extra iron to replace what's lost during menstruation; teen boys need extra iron to support rapid growth.

Deficiency can lead to fatigue, irritability and headaches. An iron overdose is life threatening, so never give iron supplements without consulting a health professional.

Multivitamin

Studies have shown that children taking multivitamins may do better academically and exhibit less antisocial behavior; some children with ADHD improve with supplementation.

Supplements do not substitute for a healthy, balanced diet. Follow label recommendations.

Vitamin B complex

This is a necessary cofactor in lots of neural activity; some experts report success giving B complex to children with ADHD.

Most B vitamins have no side effects. B3 (niacin) can cause skin flushing; time-released niacin has been associated with liver damage; very high doses of B6 can cause numbness or tingling.

Vitamin B12 (cobalamin)

B12 helps build strong myelin sheath to insulate nerves; it is important for DNA synthesis and necessary for healthy red blood cells. Because B12 is found in animal products, vegans risk deficiency.

Soy contains B12, but it's not as active as the form found in animal products.

Vitamin C (ascorbic acid)

This antioxidant boosts the immune system; helps with bone development, collagen formation and connective tissue that stabilizes muscles and bones; enhances iron absorption; and is important to neurotransmitters, gum health and hormone and amino acid synthesis.

Many nutritionists believe the older teen (and adult) daily dose should be as high as 200 mg. Too much vitamin C can cause diarrhea.

Vitamin D

This vitamin promotes calcium and phosphorus absorption for strong bones. Breastfed infants, children in cloudy climates, and vegans are at risk for deficiency. Supplementing infants has been associated with greater bone density later in life.

This is the only vitamin a baby needs more of than adults do. Consult with health experts before giving any supplement to infants. Sunshine naturally stimulates the body's vitamin D production.

Vitamin E

This antioxidant enhances immunity and protects cell membranes.

Excess E can lead to muscle weakness, fatigue, nausea and diarrhea.

Zinc

Zinc is important for cell division, hormone manufacture, immunity, skin healing, growth, vision and metabolism. Vegetarians can be at risk for deficiency.

Pregnant and nursing women need 11-40 mg zinc/day.

*Check with a health care provider for doses that are appropriate for the age of your child.